The developers have thought about turning shrine effects into power-up type orbs just so that they can appear more randomly as drops off enemies instead of having to be placed in levels. [1] They never intended to replace health potions with the healing-orb system and don't think it would be necessary or beneficial given the other changes they've made to health recovery. [1, 2, 3]

The methods of health recovery should have limits but be predictable and dependable. It is not fun to have to rely on some amount of luck to recover health. [1] They do actually like the idea of random instant-use drops like healing orbs and shrine-like buffs, just not as the sole means of healing. [2]
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